Hopefully you are reading this before your catalytic converter was stolen on your Gen 2 (2004-2009) Toyota Prius. If yours was stolen there are some options you have depending on what state you are in. You can either replace the catalytic converter with a dealership new OEM converter ($1800-2200 roughly), or you can replace it with an eBay 48 state legal catalytic converter for $150-200, or you can try to find a used catalytic converter and an installer to weld it.

This is by no means legal advice on what is legal in your state or not with smog laws. I can tell you that in California it is illegal to install a used catalytic converter (for a shop) and the catalytic converter is supposed to be checked when any smog shop smogs your vehicle. Therefore, if you install the eBay $150 dollar catalytic converter after your CA legal cat is stolen, you may get a fail for “tampering” on your CA smog.

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Options for Buying Catalytic Converters for 2004-2009 Gen 2 Prius:

eBay Special which bolts onto the existing cut off pipe. This takes a little bit of luck and some patience upon installing and I believe these are illegal in both California (for sure) and New York. If you live in any state without strict smog laws (double check) this would be the way I would go if my cat was stolen. Here is a link to an ebay search and you can see your options.
Buy an aftermarket California legal catalytic converter. You will need to do your own research on this and cross reference the aftermarket catalytic converter numbers with the aftermarket catalytic converter database search linked here.
Check facebook marketplace or Craigslist for used catalytic converters from scrap or crashed cars. I can’t tell you whether or not this is legal in your state so proceed at your own risk. This is by far the cheapest option to get your car back on the road with a legal catalytic converter in NY or CA without breaking the bank.

How to Protect Your Catalytic Converter from being Stolen:

There are a couple of very ingenious ways of protecting the cat on your 2004-2009 Prius. The first one is by installing a “shield” by numerous manufacturers which bolts on the underside of your Prius and discourages thieves from stealing. This is because in order to get your catalytic converter out they slide under your car (usually the jack it up first) and they use a sawzall to cut it out. With a metal shield placed in their way, they now would have to cut through the shield first in order to steal your catalytic converter (causing a ton of noise).

Catalytic Converter Shield 2004-2009 Prius — One option for a shield you install to protect your Catalytic Converter from thieves.

Here are some brands that are worth considering / options you have to protect the cat on your car:

The shields cost between $100-180 and can be installed DIY pretty easily. Just follow instructions on this youtube video for installing either shield (same basic concepts)

Best Aftermarket Catalytic Converters:

If you are not in CA, NY, or ME. These are some of the better options for aftermarket converters if your original equipment (OEM) catalytic converter was unfortunately stolen.

How to Install Aftermarket Catalytic Converter 2004-2009 Prius?

Most thieves are going to cut your catalytic converter and leave the rear of your exhaust in place. That is why you see a lot of aftermarket converters sold with a U-bolt and new donut gasket. This is so you can bolt on your aftermarket catalytic converter directly onto the left cut part and reinstall the two bolts holding it to the exhaust manifold and be on your way. Having done this myself here are a couple of tips I have for the install.

Use an exhaust clamp where the two pieces meet at the rear. This will be better than the ujoint (or install that over the clamp) to help ensure there aren’t any exhaust leaks.
Use exhaust putty at this connection point to help reduce leaks (before you install the universal clamp above slather the exhaust with this exhaust putty then clamp over it and let it cure overnight.

Do I have to have my new catalytic converter installed by a welder?

You do not, if you follow my tips above and the thieves left you with a nice cut. However, if you want the easier install then have your Prius catalytic converter installed at an exhaust shop and have them weld it on. This will be more expensive and means you can’t replace it as easily in the future, but if you won’t want to deal with the hassle of installing it yourself this is the better option. When I first replaced mine on my 2005 Prius I was getting all sorts of exhaust leaks just using the U-clamp the catalytic converter came with. It wasn’t until I installed the clamp and exhaust putty that my car now is leak free and as quiet as normal.

What if my Cat wasn’t stolen but I have a P0420 Code?

This means your car is detecting that the catalytic converter is not working right anymore. If this is the only code your car has stored in its computer and the car is running well then 9/10 the catalytic converter has just failed. However, if you have any other problems with your car like a misfire, you need to fix that problem first before replacing catalytic converters. This is because the cat works by removing unburnt carbon from the exhaust. If you have a misfire, then you are working the catalytic converter extremely hard, and that is what caused it to fail prematurely. Therefore, if you just have a P420 and nothing else is wrong with the car, replace the CAT. Otherwise pay a shop for diagnosis or do more diagnosis yourself before spending anymore money.

FAQ:

Is it legal to sell a used catalytic converter in California?

It is illegal to sell used catalytic converters in California. If you cannot find an aftermarket CARB compliant catalytic converter for the Prius, you are not allowed by law to buy a used one. Many aftermarket sellers of catalytic converters on eBay or Amazon will not ship their catalytic to California addresses as well. Your only option might be to go to the Toyota dealer and have them install a brand new OEM CA legal catalytic converter (at a very high cost). As I explained above there are other options if you are wanting to do it yourself or don’t live in a smog strict state.

Why are thieves stealing Prius Cats?

This is because they are extremely easy to remove and steal and are worth a lot of money at scrap yards. Thieves are probably selling these for scrap at around $600-1000 depending on the state. So as you can see if you drive your 04-09 Prius with no protection into any city like San Francisco, Oakland, Vallejo, San Jose, you are asking for the cat to be stolen. Don’t be dumb and get a protector installed ASAP before it happens to you.

Should I get comprehensive insurance to cover a stolen cat?

Yes. I carry comprehensive insurance on my Prius for this exact reason. Call your insurance company and make sure they cover a stolen catalytic converter, but most will. The price increase for this coverage may be a lot less than you think, and if it is stolen they may “total” the car and give you a check for the entire cars value. This is because with the OEM catalytic converters being so expensive, more often than not they are worth more than the entire Prius. I would definitely upgrade to comprehensive insurance if you live anywhere that theft is a problem.

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